Ultrasonic fingerprint recognition component and electronic device

Abstract

The present invention provides an ultrasonic fingerprint recognition component, which includes a cover plate, an ultrasonic sensor, and a display panel. The ultrasonic sensor is disposed between the cover plate and the display panel. The ultrasonic sensor includes a TFT substrate disposed on the side close to the display panel, and a piezoelectric layer and a conductive layer sequentially disposed on the TFT substrate. The piezoelectric layer is prepared by coating a piezoelectric material mixed with an organic solvent on a substrate and then performing crystallization and polarization treatments. The organic solvent includes at least one of methyl ethyl ketone, propylene glycol methyl ether acetate, and dimethylacetamide. In the ultrasonic fingerprint recognition component provided by the present invention, the ultrasonic sensor is disposed between the cover plate and the display panel. Since the thickness of the cover plate is limited, the ultrasonic signal will not be affected by the cover plate and has strong penetrability, and the fingerprint recognition process is no longer limited by the display panel. At the same time, the light transmittance of the piezoelectric layer is uniform and excellent in light transmission performance, which improves the fingerprint recognition speed and accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of fingerprint recognition, and particularly to an ultrasonic fingerprint recognition component and an electronic device. Background Art

[0002] Currently, in the mobile phone industry, fingerprint unlocking is generally performed in a small specific area, and it is impossible to achieve blind unlocking and add related APP functions through fingerprint unlocking. To meet the requirements of full-screen mobile phones and improve the user experience of mobile phone terminals, full-screen fingerprint recognition has emerged. However, in current full-screen fingerprint recognition solutions, especially in ultrasonic fingerprint recognition solutions, the ultrasonic sensor is placed at the back end of the display screen and the touch screen, which necessarily puts higher requirements on the penetrability of ultrasonic waves. Therefore, it is urgent to develop new ultrasonic fingerprints that can be used for full-screen display. Summary of the Invention

[0003] In view of this, the present invention provides an ultrasonic fingerprint recognition component, in which the ultrasonic sensor is arranged between the cover plate and the display panel. The ultrasonic sensor is used to transmit and receive ultrasonic signals and convert the ultrasonic signals into electrical signals to form a fingerprint recognition image. Since the thickness of the cover plate is limited, the ultrasonic signal will not be affected by the cover plate and has strong penetrability. Compared with the prior art, the fingerprint recognition process is no longer affected by the display panel, and the effect of increasing the fingerprint recognition speed and accuracy can be achieved without improving the penetrability of ultrasonic waves. At the same time, the light transmittance of the piezoelectric layer is uniform and excellent in light transmission performance, further improving the fingerprint recognition speed and accuracy. The ultrasonic fingerprint recognition component can be designed as a standardized component to achieve large-scale application in different scenarios.

[0004] In a first aspect, the present invention provides an ultrasonic fingerprint recognition component, including a cover plate, an ultrasonic sensor, and a display panel. The ultrasonic sensor is arranged between the cover plate and the display panel. The ultrasonic sensor includes a TFT substrate disposed on a surface close to the display panel side and a piezoelectric layer and a conductive layer sequentially disposed on the TFT substrate;

[0005] The piezoelectric layer is prepared by mixing a piezoelectric material with an organic solvent, coating it on a substrate, and then performing crystallization and polarization treatment. The organic solvent includes at least one of methyl ethyl ketone, propylene glycol methyl ether acetate, and dimethylacetamide.

[0006] In the present invention, the ultrasonic sensor is arranged between the cover plate and the display panel. The thickness of the cover plate is limited, and the ultrasonic signal will not be affected by the cover plate. At the same time, compared with the prior art, the ultrasonic signal is no longer affected by the display panel during the fingerprint recognition process. Therefore, the ultrasonic signal has strong penetrability during the recognition process, and the recognition speed and accuracy during the fingerprint recognition process can be improved.

[0007] In the present invention, the piezoelectric layer is used to convert electrical signals and ultrasonic signals into each other, and is used to transmit and receive ultrasonic signals. The conductive layer forms a voltage with the TFT substrate and applies it to the piezoelectric layer to enable the piezoelectric layer to play a conversion role. At the same time, the piezoelectric layer is formed by crystallization and polarization after mixing a piezoelectric material with an organic solvent. The organic solvent includes at least one of methyl ethyl ketone, propylene glycol methyl ether acetate, and dimethylacetamide, which is beneficial to making the light transmittance of the piezoelectric layer uniform and excellent in light transmission performance.

[0008] Optionally, the organic solvent includes methyl ethyl ketone and propylene glycol methyl ether acetate. When the organic solvent includes methyl ethyl ketone and propylene glycol methyl ether acetate, the molar ratio of methyl ethyl ketone to propylene glycol methyl ether acetate can be, but is not limited to, 1:(1 - 2). This ratio of methyl ethyl ketone and propylene glycol methyl ether acetate is beneficial to making the thickness of the piezoelectric layer uniform, thereby making the light transmittance of the piezoelectric layer consistent.

[0009] Optionally, the piezoelectric material includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polycarbonate, polyvinylidene difluoride, and polyvinyl chloride. The piezoelectric material used in the present invention can make the piezoelectric effect of the piezoelectric layer good, the signal penetration ability strong, and at the same time has good light transmittance, which is beneficial to improving the recognition effect of the ultrasonic sensor.

[0010] Further, the molar ratio of the piezoelectric material to the organic solvent is (0.5 - 3):1, so that the particle size of the piezoelectric material in the prepared piezoelectric layer is less than 15 nm and the crystallinity is improved, thereby improving the light transmittance of the piezoelectric layer. Furthermore, the molar ratio of the piezoelectric material to the organic solvent is (0.8 - 2.5):1, so that the particle size of the piezoelectric material in the prepared piezoelectric layer is less than 13 nm, further improving the light transmittance of the piezoelectric layer.

[0011] Further, the crystallization is carried out at 130°C - 150°C for 0.5 h - 5 h, which can make the crystallinity of the piezoelectric layer greater than 68% and reduce the particle size of the piezoelectric material, thereby improving the light transmittance of the piezoelectric layer. Furthermore, the conditions for the crystallization are carried out at 135°C - 145°C for 1 h - 4 h, which can make the crystallinity of the piezoelectric layer greater than 70%, further improving the light transmittance of the piezoelectric layer.

[0012] Optionally, the thickness of the piezoelectric layer is less than 20 μm. Further, the thickness of the piezoelectric layer is less than 10 μm. Furthermore, the thickness of the piezoelectric layer is 1 μm - 8 μm. When the thickness of the piezoelectric layer is less than 20 μm, the light transmittance is good, the signal penetration ability is strong, the fingerprint recognition speed is fast, and the recognition effect of the acoustic wave fingerprint sensor is further improved; when the thickness of the piezoelectric layer is less than 10 μm, the recognition effect of the acoustic wave fingerprint sensor can be further improved.

[0013] Optionally, the TFT substrate includes a substrate and thin film transistors arranged in an array on the substrate. Specifically, the substrate can be, but is not limited to, a glass substrate provided with a polyethylene terephthalate (PET) film. In the present invention, the light transmittance of the substrate only needs to meet the actual requirements, and the material of the substrate is not limited.

[0014] Optionally, the thickness of the TFT substrate is 150 μm - 500 μm. Further, the thickness of the TFT substrate is 200 μm - 450 μm. Specifically, the thickness of the TFT substrate can be, but is not limited to, 150 μm, 180 μm, 220 μm, 290 μm, 350 μm or 420 μm. The thickness of the TFT substrate does not exceed 500 μm, which not only has a good supporting effect but also ensures the required light transmittance.

[0015] Optionally, the material of the conductive layer is at least one of indium tin oxide, nano silver, and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid). The conductive layer is selected from materials with high light transmittance, which improves the light transmittance of the conductive layer.

[0016] Optionally, the thickness of the conductive layer is 10 μm - 20 μm. Further, the thickness of the conductive layer is 12 μm - 17 μm. Still further, the thickness of the conductive layer is 13 μm - 16 μm. The smaller the thickness of the conductive layer, the higher the light transmittance.

[0017] Optionally, the display panel has a display area, and the orthographic projection of the ultrasonic sensor on the display panel partially or completely covers the display area.

[0018] Optionally, the cover plate has a visible area, and the orthographic projection of the ultrasonic sensor on the cover plate partially or completely covers the visible area.

[0019] In the present invention, when the ultrasonic sensor completely covers the display area of the display panel and / or the ultrasonic sensor completely covers the visible area of the cover plate, full-screen fingerprint recognition can be achieved, which is beneficial for blind unlocking and improves the user experience; at the same time, it can also be combined with a new software design, and various recognition methods can be used, such as single-finger recognition, multi-finger recognition, specific recognition gestures, etc. Moreover, corresponding multiple recognition effects can be provided according to various recognition methods. For example, when the ultrasonic fingerprint recognition component is applied to a mobile phone, different recognition methods can be used to achieve differences in the interface after the mobile phone is unlocked, bringing a new experience to the user.

[0020] In the present invention, when the ultrasonic sensor partially covers the display area of the display panel and / or the ultrasonic sensor partially covers the visible area of the cover plate, the manufacturing cost of the ultrasonic sensor can be saved.

[0021] Optionally, the cover plate includes a cover plate substrate, which is at least one of a transparent glass plate, a transparent ceramic plate, and a transparent organic plate. Further, the cover plate further includes an ink layer, which is disposed on the surface of the cover plate substrate close to the ultrasonic sensor. Further still, the ink layer is disposed at the four peripheral edges of the cover plate.

[0022] Optionally, a surface treatment layer is disposed on the surface of the cover plate away from the ultrasonic sensor. Further, the surface treatment layer includes at least one of an anti-glare layer, an anti-reflection layer, and an anti-fingerprint layer. In the present invention, the provision of the surface treatment layer enables the ultrasonic identification component to have functions of anti-glare, anti-reflection, and anti-fingerprint, improves the display effect of the ultrasonic identification component, and improves the comfort of user use.

[0023] Optionally, the ultrasonic sensor further includes a first bonding layer, which is disposed on the surface of the conductive layer close to the cover plate. Further, the first bonding layer includes a die attach film (DAF). Further still, the thickness of the first bonding layer is 30 μm - 60 μm. Further still, the thickness of the first bonding layer is 35 μm - 60 μm. In the present invention, the first bonding layer is used to protect the conductive layer from oxidation and to adjust the frequency to adapt to cover plates of different thicknesses.

[0024] Optionally, the ultrasonic fingerprint identification component further includes a circuit board, which is respectively connected to the TFT substrate and the conductive layer. Further, the circuit board is a flexible circuit board. In the present invention, the first bonding layer is also used to compensate for the step difference that the circuit board is higher than the conductive layer. At the same time, the circuit board is placed outside the path through which the ultrasonic wave conducts to the contact object, and the ultrasonic wave does not pass through the circuit board during the conduction process, thereby avoiding the influence of the circuit board on the ultrasonic wave conduction.

[0025] Optionally, the circuit board is respectively connected to the TFT substrate and the conductive layer through an anisotropic conductive film adhesive. In the present invention, the circuit board is connected to the ultrasonic sensor through an anisotropic conductive film (ACF) to form an external-mounted identification module, which is attached under the cover plate to further realize the full-screen fingerprint identification function. In the present invention, the conductive particles of the ACF connect the circuit board and the TFT substrate to conduct in the Z-axis direction and be insulated in the X and Y-axis directions.

[0026] Optionally, the ultrasonic fingerprint identification component further includes a driving chip, which is disposed on the circuit board. The driving chip provides a control signal to the ultrasonic sensor to enable the ultrasonic sensor to emit ultrasonic waves, and can also receive the feedback electrical signal to identify fingerprints.

[0027] Optionally, the ultrasonic fingerprint recognition component further includes a second adhesive layer disposed between the ultrasonic sensor and the cover plate to connect the ultrasonic sensor and the cover plate. Further, the material of the second adhesive layer includes OCA optical adhesive. In the present invention, the first adhesive layer is further used to compensate for the possible thickness unevenness that may occur when directly using the second adhesive layer, improve the flatness of the plane, and is more conducive to the conduction of ultrasonic waves. At the same time, the second adhesive layer has a relatively large Young's modulus. For example, the Young's modulus of OCA is large, which avoids weakening of the ultrasonic signal.

[0028] Optionally, the ultrasonic fingerprint recognition component further includes a third adhesive layer disposed between the ultrasonic sensor and the display panel to connect the ultrasonic sensor and the display panel. Further, the material of the third adhesive layer includes OCA optical adhesive.

[0029] In the present invention, the ultrasonic fingerprint recognition component can be designed as a standardized component to achieve large-scale applications in different scenarios. Specifically, it is not limited to directly installing the ultrasonic fingerprint recognition component between the mobile phone assembly parts, and the assembly of the fingerprint recognition structure in the mobile phone can be realized, which can not only improve the production and assembly efficiency, but also save processes.

[0030] In a second aspect, the present invention provides an electronic device including the ultrasonic fingerprint recognition component described in the first aspect.

[0031] Advantages of the present invention:

[0032] In the ultrasonic fingerprint recognition component provided by the present invention, the ultrasonic sensor is disposed between the cover plate and the display panel. The ultrasonic sensor is used to transmit and receive ultrasonic signals and convert the ultrasonic signals into electrical signals to form a fingerprint recognition image. Since the thickness of the cover plate is limited, the ultrasonic signal will not be affected by the cover plate and has strong penetrability. Compared with the prior art, the fingerprint recognition process is no longer affected by the display panel, and the effect of increasing the fingerprint recognition speed and accuracy can be achieved without improving the penetrability of the ultrasonic wave. At the same time, the light transmittance of the piezoelectric layer therein is uniform and excellent in light transmittance performance, further improving the fingerprint recognition speed and accuracy. The ultrasonic fingerprint recognition component can be designed as a standardized component to achieve large-scale applications in different scenarios. The ultrasonic fingerprint recognition component can be used in an electronic device to improve the fingerprint recognition speed and security of the electronic device. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Figure 1 Schematic diagram of a structure of an ultrasonic fingerprint recognition component provided for the implementation of the present invention. Specific implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0036] Please refer to Figure 1 , which is a schematic diagram of a structure of an ultrasonic fingerprint recognition component provided for an embodiment of the present invention. The ultrasonic fingerprint recognition component includes a cover plate 10, an ultrasonic sensor 20, and a display panel 30. The ultrasonic sensor 20 is disposed between the cover plate 10 and the display panel 30. The ultrasonic sensor 20 includes a TFT substrate 201 disposed on a surface closer to the display panel 30, and a piezoelectric layer 202 and a conductive layer 203 sequentially disposed on the TFT substrate 201. The piezoelectric layer 202 is prepared by mixing a piezoelectric material with an organic solvent, coating the mixture on a substrate, and then performing crystallization and polarization treatments. The organic solvent includes at least one of methyl ethyl ketone, propylene glycol methyl ether acetate, and dimethylacetamide.

[0037] In the implementation manner of the present invention, the ultrasonic sensor 20 is disposed between the cover plate 10 and the display panel 30. The thickness of the cover plate 10 is limited, and the ultrasonic signal will not be affected by the cover plate 10. At the same time, compared with the prior art, the ultrasonic signal is no longer affected by the display panel 30 during the fingerprint recognition process. Therefore, the ultrasonic signal has strong penetrability during the recognition process, and the recognition speed and accuracy during the fingerprint recognition process can be improved.

[0038] In the implementation manner of the present invention, the piezoelectric layer 202 is used to convert electrical signals and ultrasonic signals into each other, and is used to transmit and receive ultrasonic signals. The conductive layer 203 forms a voltage with the TFT substrate 201 and is applied to the piezoelectric layer 202 to enable the piezoelectric layer 202 to realize the conversion of electrical signals and ultrasonic signals. At the same time, the piezoelectric layer 202 is formed by crystallization and polarization after mixing a piezoelectric material with an organic solvent. The organic solvent includes at least one of methyl ethyl ketone, propylene glycol methyl ether acetate, and dimethylacetamide, which is beneficial to making the light transmittance of the piezoelectric layer 202 uniform and excellent in light transmission performance.

[0039] In a specific embodiment of the present invention, an electrical signal is transmitted to the piezoelectric layer 202 through the TFT substrate 201 and the conductive layer 203 to form an ultrasonic signal; the piezoelectric layer 202 emits the ultrasonic signal and penetrates through the cover plate 10. The ultrasonic signal propagates to the fingerprint ridges and valleys, and the ultrasonic signal after reflection returns to the piezoelectric layer 202. The conductive layer 203 and the TFT substrate 201 convert the ultrasonic signal after reflection into an electrical signal to obtain a fingerprint image.

[0040] In an embodiment of the present invention, the organic solvent includes at least one of methyl ethyl ketone, propylene glycol methyl ether acetate, and dimethylacetamide. The organic solvent used in the present invention can better dissolve the piezoelectric material, making the obtained piezoelectric layer 202 have good transparency. Further, the organic solvent includes methyl ethyl ketone and propylene glycol methyl ether acetate. When the organic solvent includes methyl ethyl ketone and propylene glycol methyl ether acetate, the molar ratio of methyl ethyl ketone to propylene glycol methyl ether acetate can be but is not limited to 1:(1 - 2). This ratio of methyl ethyl ketone and propylene glycol methyl ether acetate is beneficial to make the thickness of the piezoelectric layer 202 uniform, so that the light transmittance of the piezoelectric layer is consistent. In the present invention, the particle size of the piezoelectric material in the piezoelectric layer prepared by the above method is less than 17 nm, and the crystallinity is greater than 65%, making the overall light transmittance of the piezoelectric layer uniform and the light transmittance performance of the piezoelectric layer excellent.

[0041] In an embodiment of the present invention, the piezoelectric material includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polycarbonate, polyvinylidene difluoride, and polyvinyl chloride. The piezoelectric material used in the present invention can make the piezoelectric effect of the piezoelectric layer 202 good, the signal penetration ability strong, and at the same time has good light transmittance, which is beneficial to improving the recognition effect of the ultrasonic sensor.

[0042] In a specific embodiment of the present invention, the piezoelectric layer 202 is obtained by mixing a piezoelectric material and an organic solvent to obtain a mixed slurry, coating the mixed slurry on a substrate, separating it from the substrate after crystallization to obtain a piezoelectric blank layer, combining the piezoelectric blank layer with the TFT substrate 201, and then performing polarization treatment.

[0043] In an embodiment of the present invention, the molar ratio of the piezoelectric material to the organic solvent is (0.5 - 3):1, so that the particle size of the piezoelectric material in the obtained piezoelectric layer 202 is less than 15 nm and the crystallinity is improved, thereby improving the light transmittance of the piezoelectric layer. Further, the molar ratio of the piezoelectric material to the organic solvent is (0.8 - 2.5):1, so that the particle size of the piezoelectric material in the obtained piezoelectric layer 202 is less than 13 nm, further improving the light transmittance of the piezoelectric layer 202.

[0044] In the embodiments of the present invention, crystallization is carried out at 130°C - 150°C for 0.5 h - 5 h, which can make the crystallinity of the piezoelectric layer greater than 68% and reduce the particle size of the piezoelectric material, thereby improving the light transmittance of the piezoelectric layer. Further, the crystallization conditions are to be carried out at 135°C - 145°C for 1 h - 4 h, which can make the crystallinity of the piezoelectric layer greater than 70%, further improving the light transmittance of the piezoelectric layer. Specifically, the crystallization conditions can be, but are not limited to, treatment at 144°C for 4 h, 150°C for 1 h, or 135°C for 3 h.

[0045] In an embodiment of the present invention, when the molar ratio of the piezoelectric material to the organic solvent is mixed at (0.5 - 3):1, coated on a substrate, and treated at 130°C - 150°C for 0.5 h - 5 h and then subjected to polarization treatment to form the piezoelectric layer 202, at this time, the particle size of the piezoelectric material in the piezoelectric layer 202 is 6 nm - 13 nm, the crystallinity is 75% - 85%, and the light transmittance of the piezoelectric layer 202 is greater than 85%.

[0046] In an embodiment of the present invention, when the molar ratio of the piezoelectric material to the organic solvent is mixed at (0.8 - 2.5):1, coated on a substrate, and treated at 135°C - 145°C for 1 h - 4 h and then subjected to polarization treatment to form the piezoelectric layer 202, at this time, the particle size of the piezoelectric material in the piezoelectric layer 202 is 8 nm - 12 nm, the crystallinity is 79% - 85%, and the light transmittance of the piezoelectric layer 202 is greater than 90%.

[0047] In a specific embodiment of the present invention, when the molar ratio of the piezoelectric material to the organic solvent is mixed at 2:1, coated on a substrate, and treated at 144°C for 4 h and then subjected to polarization treatment to form the piezoelectric layer 202, at this time, the particle size of the piezoelectric material in the piezoelectric layer 202 is about 10 nm, the crystallinity is 82%, and it is measured that the light transmittance of the piezoelectric layer 202 is greater than 91%.

[0048] In the embodiments of the present invention, the thickness of the piezoelectric layer 202 is less than 20 μm. Further, the thickness of the piezoelectric layer 202 is less than 10 μm. Furthermore, the thickness of the piezoelectric layer 202 is 1 μm - 8 μm. When the thickness of the piezoelectric layer 202 is less than 20 μm, the light transmittance is good, the signal penetration ability is strong, the fingerprint recognition speed is fast, and the recognition effect of the acoustic wave fingerprint sensor is further improved; when the thickness of the piezoelectric layer 202 is less than 10 μm, the recognition effect of the acoustic wave fingerprint sensor can be further improved.

[0049] In a specific embodiment of the present invention, the preparation of the piezoelectric layer 202 may, but is not limited to, mixing polyvinylidene fluoride with methyl ethyl ketone and propylene glycol monomethyl ether acetate to obtain a mixed slurry; providing a substrate, coating the mixed slurry on the substrate, and after crystallization at 144 °C for 4 h, forming a piezoelectric green body layer on the substrate; peeling the piezoelectric green body layer from the substrate, placing it on the TFT substrate 201, and then through polarization treatment, forming the piezoelectric layer 202. Among them, the transmittance of the obtained piezoelectric layer 202 at a wavelength of 550 nm is greater than 91%.

[0050] In an embodiment of the present invention, the TFT substrate 201 includes a substrate and thin film transistors arranged in an array on the substrate. The thin film transistors arranged in an array are used to detect signals at each position of the piezoelectric layer 202 to obtain corresponding fingerprint information. Further, the TFT substrate 201 further includes a circuit connecting each thin film transistor. Specifically, the substrate may, but is not limited to, be a glass substrate provided with a polyethylene terephthalate (PET) film. In the present invention, the transmittance of the substrate only needs to meet the actual requirements, and the material of the substrate is not limited.

[0051] In an embodiment of the present invention, the thickness of the TFT substrate 201 is 150 μm - 500 μm. Further, the thickness of the TFT substrate 201 is 200 μm - 450 μm. Specifically, the thickness of the TFT substrate 201 may, but is not limited to, be 150 μm, 180 μm, 220 μm, 290 μm, 350 μm or 420 μm. In this way, the thickness of the TFT substrate 201 is within a suitable range, which can not only have good support strength, but also ensure good transmittance and avoid excessive weakening of the displayed image.

[0052] In an embodiment of the present invention, the material of the conductive layer 203 may, but is not limited to, be at least one of indium tin oxide, nano silver, and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid). The conductive layer 203 is made of a material with high transmittance, which improves the transmittance of the conductive layer. Specifically, the conductive layer 203 may, but is not limited to, be prepared by screen printing silver paste and then sintering.

[0053] In an embodiment of the present invention, the thickness of the conductive layer 203 is 10 μm - 20 μm. Further, the thickness of the conductive layer 203 is 12 μm - 17 μm. Further still, the thickness of the conductive layer 203 is 13 μm - 16 μm. Specifically, the thickness of the conductive layer 203 may, but is not limited to, be 11 μm, 14 μm, 14.7 μm, 15 μm or 18.5 μm. The smaller the thickness of the conductive layer 203, the higher the transmittance and the faster the recognition speed.

[0054] In an embodiment of the present invention, the display panel 30 has a display area, and the orthographic projection of the ultrasonic sensor 20 on the display panel 30 covers or completely covers the display area.

[0055] In an embodiment of the present invention, the cover plate 10 has a visible area, and the orthographic projection of the ultrasonic sensor 20 on the cover plate 10 covers or completely covers the visible area, that is, the area of the orthographic projection of the ultrasonic sensor 20 on the cover plate 10 is greater than or equal to the area of the visible area. Further, the orthographic projection of the ultrasonic sensor 20 on the cover plate 10 covers the visible area and the area of the orthographic projection is greater than the area of the visible area, which is more conducive to full-screen fingerprint recognition.

[0056] In an embodiment of the present invention, when the ultrasonic sensor 20 completely covers the display area of the display panel 30 and / or the ultrasonic sensor 20 completely covers the visible area of the cover plate 10, full-screen fingerprint recognition can be achieved, which is beneficial to blind unlocking and improves the user experience; at the same time, it can also be combined with a new software design, and various recognition methods can be used, such as single-finger recognition, multi-finger recognition, specific recognition gestures, etc. According to various recognition methods, corresponding multiple recognition effects can also be provided. For example, when the ultrasonic fingerprint recognition component is applied to a mobile phone, the interface difference after the mobile phone is unlocked can be realized according to different recognition methods. For example, single-finger recognition can display hidden files, hidden APPs, etc., while multi-finger recognition cannot display hidden files, hidden APPs, etc., which can bring a new experience to users.

[0057] In an embodiment of the present invention, when the ultrasonic sensor 20 partially covers the display area of the display panel 30 and / or the ultrasonic sensor 20 partially covers the visible area of the cover plate 10, the manufacturing cost of the ultrasonic sensor 20 can be saved.

[0058] Please refer to Figure 1 , in an embodiment of the present invention, the cover plate 10 includes a cover plate substrate 101, and the cover plate substrate 101 is at least one of a transparent glass plate, a transparent ceramic plate, and a transparent organic plate. Further, the cover plate 10 further includes an ink layer 102, and the ink layer 102 is disposed on the surface of the cover plate substrate 101 close to the ultrasonic sensor 20. Further still, the ink layer 102 is disposed at the four peripheral edges of the cover plate 10. In the present invention, the cover plate 10 can be a completely transparent component, and the whole is a visible area, or an ink layer 102 is disposed on the cover plate substrate 101 of the cover plate 10, and the area not covered by the ink layer 102 is the visible area. Specifically, the ink layer 102 can be disposed on the cover plate substrate 101 by, but not limited to, screen printing and other methods.

[0059] In an embodiment of the present invention, a surface treatment layer is provided on the surface of the cover plate 10 on the side away from the ultrasonic sensor 20. Further, the surface treatment layer includes at least one of an anti-glare layer, an anti-reflection layer, and an anti-fingerprint layer. In the present invention, providing the surface treatment layer enables the ultrasonic recognition component to have the functions of anti-glare, anti-reflection, and anti-fingerprint, improving the display effect of the ultrasonic recognition component and the comfort of user use.

[0060] Please refer to Figure 1 , in an embodiment of the present invention, the ultrasonic sensor 20 further includes a first bonding layer 204, and the first bonding layer 204 is provided on the surface of the conductive layer 203 on the side close to the cover plate 10. Further, the first bonding layer 204 includes a die attach film (DAF). Further, the thickness of the first bonding layer 204 is 30μm - 60μm. Further still, the thickness of the first bonding layer 204 is 35μm - 60μm. Specifically, the thickness of the first bonding layer 204 can be, but is not limited to, 33μm, 38μm, 43μm, 47.2μm, 51μm, or 55μm. In the present invention, the first bonding layer 204 is used to protect the conductive layer 203 from being oxidized and to adjust the frequency to adapt to cover plates 10 of different thicknesses.

[0061] In an embodiment of the present invention, the ultrasonic fingerprint recognition component further includes a circuit board 40, and the circuit board 40 is respectively connected to the TFT substrate 201 and the conductive layer 203. Further, the circuit board 40 is a flexible circuit board. The first bonding layer 204 is also used to compensate for the step difference where the circuit board 40 is higher than the conductive layer 203. At the same time, the circuit board 40 is placed outside the path through which the ultrasonic wave conducts to the contact object, and the ultrasonic wave does not pass through the circuit board 40 during the conduction process, thereby avoiding the influence of the circuit board 40 on the ultrasonic wave conduction.

[0062] In an embodiment of the present invention, the circuit board 40 is respectively connected to the TFT substrate 201 and the conductive layer 203 through an anisotropic conductive film adhesive 50. In the present invention, the circuit board 40 is connected to the ultrasonic sensor 20 through an anisotropic conductive film (ACF) 50 to form an external-mounted recognition module, which is attached between the cover plate 10 and the display panel 30 to further realize the full-screen fingerprint recognition function. In the present invention, the conductive particles of the ACF connect the circuit board 40 and the TFT substrate 201 to conduct in the Z-axis direction and be insulated in the X and Y-axis directions.

[0063] In an embodiment of the present invention, the ultrasonic fingerprint recognition component further includes a driving chip 60, and the driving chip 60 is disposed on the circuit board 40. In the present invention, the driving chip 60 may be, but is not limited to, an ASIC (Application Specific Integrated Circuit) chip. The driving chip 60 provides a control signal to the ultrasonic sensor 20 to enable the ultrasonic sensor 20 to emit ultrasonic waves, and at the same time, it can also receive the feedback electrical signal to recognize the fingerprint.

[0064] In an embodiment of the present invention, the ultrasonic fingerprint recognition component further includes a second adhesive layer 70, and the second adhesive layer 70 is disposed between the ultrasonic sensor 20 and the cover plate 10 to connect the ultrasonic sensor 20 and the cover plate 10. Further, the material of the second adhesive layer 70 includes OCA optical adhesive. In the present invention, the first adhesive layer 204 is also used to make up for the problem of uneven thickness that may occur when directly using the second adhesive layer 70, improve the flatness of the plane, and is more conducive to the transmission of ultrasonic waves. The second adhesive layer 70 has a relatively large Young's modulus. For example, the Young's modulus of OCA is large, which can avoid weakening of the ultrasonic signal.

[0065] In an embodiment of the present invention, the ultrasonic fingerprint recognition component further includes a third adhesive layer 80, and the third adhesive layer 80 is disposed between the ultrasonic sensor 20 and the display panel 30 to connect the ultrasonic sensor 20 and the display panel 30. Further, the material of the third adhesive layer 80 includes OCA optical adhesive.

[0066] In the present application, the light transmittance of the TFT substrate 201, the piezoelectric layer 202, the conductive layer 203, the first adhesive layer 204, the second adhesive layer 70, and the cover plate 10 meets the application requirements, and the selection of specific materials is not limited. For example, the light transmittance of the TFT substrate 201, the piezoelectric layer 202, the conductive layer 203, the first adhesive layer 204, the second adhesive layer 70, and the cover plate 10 is not less than 85%.

[0067] Please refer to Figure 1 , the working principle of the ultrasonic fingerprint recognition component is as follows: The fingerprint ridges (skin) in the finger are in direct contact with the ultrasonic fingerprint recognition component, and the fingerprint valleys (air) are filled with air between the ultrasonic fingerprint recognition component. Therefore, the acoustic impedance values of the ultrasonic waves propagating in the fingerprint ridges and fingerprint valleys are different, forming two different feedback signals. The ultrasonic sensor 20 receives these two feedback signals and converts them into electrical signals and sends them to the circuit board to form a fingerprint recognition image for fingerprint recognition.

[0068] The present invention provides an electronic device including the above-mentioned ultrasonic fingerprint recognition component.

[0069] The ultrasonic fingerprint recognition component provided by the present invention may be, but is not limited to, applied to electronic devices such as mobile phones, computers, tablets, and access control systems.

[0070] In the partial UD solution (under-screen fingerprint recognition) in the prior art, it is necessary to open holes in the foam, heat dissipation layer, and EMI on the back of the OLED, which destroys the integrity of the OLED. At the same time, due to the damage to the EMI, there is an easy signal interference problem. When the ultrasonic fingerprint recognition component provided by the present invention is used in an electronic device, the integrity of the display screen can be maintained.

[0071] The partial optical UD solution in the prior art can only be applied to OLED screens, and the partial ultrasonic solution is limited to OLED flexible screens. When the ultrasonic fingerprint recognition component provided by the present invention is used in an electronic device, it is not limited by the display screen and can be used for LCD, OLED, and also for display screens with Out-cell, On-cell, and In-cell structures.

[0072] The ultrasonic fingerprint recognition component provided by the present invention can achieve full-screen unlocking. At the same time, by combining full-screen unlocking with a new software design, the user experience can be improved, such as supporting one-handed blind touch unlocking, APP unlocking, multi-finger unlocking, feature point algorithms, etc., to improve the unlocking speed and security.

[0073] The ultrasonic sensor in the ultrasonic fingerprint recognition component provided by the present invention is directly located between the cover plate and the display panel. Since the thickness of the cover plate is limited, the ultrasonic wave will not be affected by the cover plate. At the same time, compared with the placement of the ultrasonic sensor at the back end of the display panel in the prior art, the ultrasonic fingerprint recognition component provided by the present invention can achieve the effect of increasing the fingerprint recognition speed and accuracy without increasing the penetration of the ultrasonic wave.

[0074] The ultrasonic fingerprint recognition component provided by the present invention can be designed as a standardized component to achieve large-scale applications in different scenarios. For example, when the ultrasonic fingerprint recognition component is directly installed between the mobile phone assembly parts, the assembly of the fingerprint recognition structure in the mobile phone can be realized, which can not only improve the production and assembly efficiency but also save processes.

[0075] In summary, in the ultrasonic fingerprint recognition component provided by the present invention, the ultrasonic sensor is arranged between the cover plate and the display panel. The ultrasonic sensor is used to transmit and receive ultrasonic signals and convert the ultrasonic signals into electrical signals to form a fingerprint recognition image. Since the thickness of the cover plate is limited, the ultrasonic signal will not be affected by the cover plate and has strong penetrability. Compared with the prior art, the fingerprint recognition process is no longer affected by the display panel, and the effect of increasing the fingerprint recognition speed and accuracy can be achieved without improving the penetrability of the ultrasonic wave. At the same time, the piezoelectric layer is formed by crystallization and polarization after being mixed with a piezoelectric material and an organic solvent. The organic solvent includes at least one of methyl ethyl ketone, propylene glycol methyl ether acetate, and dimethylacetamide, which is beneficial to making the light transmittance of the piezoelectric layer uniform and excellent in light transmittance, further improving the fingerprint recognition speed and accuracy. The ultrasonic fingerprint recognition component can be designed into a standardized component to achieve large-scale applications in different scenarios. The ultrasonic fingerprint recognition component can be used in electronic devices to improve the fingerprint recognition speed and security of the electronic devices.

[0076] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. An ultrasonic fingerprint recognition component, characterized in that, It includes a cover plate, an ultrasonic sensor, and a display panel. The ultrasonic sensor is disposed between the cover plate and the display panel. The ultrasonic sensor includes a TFT substrate disposed on a side close to the display panel, and a piezoelectric layer and a conductive layer sequentially disposed on the TFT substrate. The piezoelectric layer is prepared by mixing a piezoelectric material with an organic solvent, coating the mixture on a substrate, and then subjecting it to crystallization and polarization treatments. The organic solvent includes methyl ethyl ketone and propylene glycol monomethyl ether acetate with a molar ratio of 1:(1 - 2), or includes dimethylacetamide and methyl ethyl ketone and propylene glycol monomethyl ether acetate with a molar ratio of 1:(1 - 2). The molar ratio of the piezoelectric material to the organic solvent is (0.5 - 3):1; the crystallization is carried out at 130°C - 150°C for 0.5 h - 5 h.

2. The ultrasonic fingerprint recognition component according to claim 1, wherein The piezoelectric material includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polycarbonate, polyvinylidene difluoride, and polyvinyl chloride.

3. The ultrasonic fingerprint recognition component according to claim 1 or 2, characterized in that, The molar ratio of the piezoelectric material to the organic solvent is (0.8 - 2.5):

1.

4. The ultrasonic fingerprint recognition component according to claim 3, wherein The molar ratio of the piezoelectric material to the organic solvent is 2:

1.

5. The ultrasonic fingerprint recognition component according to claim 1, wherein, The crystallization is carried out at 135°C - 145°C for 1 h - 4 h.

6. The ultrasonic fingerprint recognition component according to claim 5, wherein, The crystallization is carried out at 144°C for 4 h.

7. The ultrasonic fingerprint recognition component according to claim 1, wherein A surface treatment layer is provided on a surface of the cover plate on a side away from the ultrasonic sensor. The surface treatment layer includes at least one of an anti-glare layer, an anti-reflection layer, and an anti-fingerprint layer.

8. An electronic device, characterized in that, It includes the ultrasonic fingerprint recognition component according to any one of claims 1 - 7.

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